I have seen many different post about the RB333 rebooting randomly.
It looks like we have found the resolution to our problem. When first installed we were using a tr-24f power supply (tranzeo 24 volt). Now with the RB333 you can run the command /sytem health print and see the voltage. We noticed that it was sitting right around 30 volts. On the RB333 overvoltage protection kicks in at 30 volts, causing our router to go down for hours at a time, and come back up when the voltage dropped.
To confirm this theory we replace the tr-24f with a 18 volt pacwireless poe, and our router has been up for 4days now.
I would be interested to hear if this helped any one else so please post your results.